and then there's the title literal translation: everything is a lie from the beginning, which kinda supports your theory from the seme's POV. anyways, i love your username, i assume you've also watched chen qing ling ヾ(☆▽☆)
Love it. Initially became a fan through the Donghua then branched out to all the other versions. Wei Ying's smile just slays me.
i agree! his smile is extremely captivating (｡♡‿♡｡)
My though is exactly same that Hayato is relative of ryou's senpai (￣∇￣")
What if it was the senpai because he knew that his kohai would not have the courage to confess
A couple theories...
One Hayato is a relative, either a younged brother or cousin to Ryou's unrequited love interest. Possobly for two reasons one, Ryou says Hayato's voice reminds him of his senpai. Two there is a moment on page 11 ( http://www.mangago.zone/read-manga/hajimari_wa_subete_uso/uu/mpn_chapter-2262217/11/) where Hayato pushes his hair behind his ear, just like Ryou's senpai did in the panel next to the one with Hayato. Having a similar voice and mannerisms makes me think he is a relative.
Hayato also asks Ryou if his face was similar to the person whose his voice was similar too. Again, a relative might have similar features too.
Two, if Hayato was in love with Ryou's senpai maybe he followed him to university where he would have seen Ryou, thus he's known Ryou since then. Maybe Ryou only had eyes for his senpai and never notice Hayato before.
Third. In this translation Hayato says "The person I love got married, and I am lonely." He does not say IN LOVE with, just a person he loves. You can love a relative without being IN LOVE with them. This line could the "lie" the title is speaking about either a full out lie or just not the full truth.
I definitely think Hayato had eyes on Ryou during the wedding and followed him. If he did know Ryou in university maybe Hayato's known about Ryou's unrequited love since then and used the line "The person I love got married, and I am lonely" knowing it would get sympathy from Ryou, giving him the in he's been looking for to get Ryou to notice him.
Just my two cents.